The demand for higher density recording in a magnetic recording medium has been increased. In order to meet the above requirement, a means to make the surface of a magnetic layer smooth has been known. However, when the surface of a magnetic layer is made smooth, the friction coefficient of contact between a magnetic layer and a running system is increased during running of the magnetic recording medium. This results in the magnetic layer of the magnetic recording medium being damaged or the magnetic layer being peeled off after a short period of use.
In many cases a video tape is put under such a harsh condition that the magnetic layer thereof is peeled off during a still mode. Under such a condition, the magnetic particles easily come off from the magnetic layer which, in many cases, causes clogging of the magnetic head.
It has been proposed in the past that abrasive (hard particles) such as corundum, silicon carbide, chromium oxide or the like should be added to a magnetic layer in order to improve the running durability of a magnetic layer. In such a case, a relatively large amount of abrasive agents must be added to effectively improve the running durability thereof. However, a large amount of abrasive agents caused the magnetic head to quickly wear out.
Furthermore, it is proposed that a fatty acid, or an ester of fatty acid and aliphatic alcohol should be added as a lubricating agent to a magnetic layer to decrease the friction coefficient.
With the recent wide spread use of portable video tape recorders and flexible disk drive apparatuses for personal computers, magnetic recording medium are used under conditions at low temperatures or high temperatures and at high humidities. Accordingly, the running durability of a magnetic recording medium must not fluctuate and must be stable under any variable conceivable conditions. However, the above-described lubricating agents are not satisfactory under all conditions.
As the size of a recording medium, particularly, a video tape and a floppy disk, is made smaller and smaller by compressing the recording wave lengths and track widths, ferromagnetic alloy particles have often been used as materials for magnetic particles instead of conventionally used iron oxide type ferromagnetic particles. Further, magnetic particles having a smaller size than conventional ones have often been used. Relatively excellent electromagnetic properties can be obtained by reducing the size of magnetic particles, but it has been difficult to simultaneously improve the running durability.